How does your brain know how to move your body? - Ivy, age 8, Victoria
Hi Ivy, thanks for asking such an interesting question!
To answer it, we'll need to look at some different parts of the brain and what they do.
First, the brain collects information
The front part of the brain plans and makes decisions. It does this after considering the different types of information it receives from "nerve cells".
This information is called "sensory" information. It comes from touch, pain, temperature, hearing, seeing, and so on.
This is what happens when, for example, we spot someone giving out chocolate on the street, we turn our heads to look at them and walk towards the chocolate.
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So how do the messages get from the brain?
The brain lives in the brain box in our head. The spinal cord lives in the spinal canal, in the back part of our body.
Tiny nerve fibres that come out of the lower part of the brain and the spinal cord connect many muscles. When they tighten, they make things move.
Some nerve fibres connect to muscles that cross the joints. Others attach to the tongue and eyeball and make them move.
Nerve cells send signals among each other, and between all the muscles and glands, including those responsible for making saliva in the mouth and digestive juices in the stomach.
A human brain has more than 100 billion nerve cells and sends messages to make us do things like walk, skip or stand up from a chair.
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Different jobs for different parts of the brain
The brain has many regions that coordinate how we move.
One part helps us work out how much force is necessary in making the movement. It also tells the brain to start the movement.
Another part plays a role in the timing of movements.
Different types of nerves also have different roles. Some help us move voluntarily - when we choose to. These nerves connect to the muscles responsible for moving our joints in different body parts, like our arms and legs.
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Another group of nerves work automatically. They sense what is happening inside our body without us consciously knowing. These nerves control the muscles in our heart, blood vessels, stomach, intestines, kidneys and other organs, helping them work properly.
What's the answer in a nutshell?
So Ivy, to sum up, the brain receives information from our senses and uses this to control our body movements.
Different parts of the brain send messages to different parts of the body to get these movements right.
Our brain can also store movements into memories that will be recalled for future use. That's why you can remember how to ride a bike, even if you haven't ridden one for months.
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Author: Arjun Burlakoti - Senior Lecturer in Anatomy and Neuroanatomy, University of South Australia